Clinical Study Confirms That Beans are the Preferred Starch Source for Diabetics

I have taught for years that beans are nutritionally superior to whole grains, and should be the preferred starch source for diabetics — I often call my dietary recommendations for diabetics “the greens and beans diet” (learn more in my book The End of Diabetes) A study published by the research group of Dr. David Jenkins (who originally developed the concept of the glycemic index) has confirmed the advantages of beans over whole grains, especially for diabetics.1

One-hundred twenty-one type 2 diabetics were split into two groups; a “low-glycemic index legume diet,” which emphasized beans and other legumes and a “high wheat fiber diet,” which emphasized whole wheat foods and other whole grains. The bean group was instructed to consume 1 cup/day of beans, lentils or other legumes and the grain group was instructed to consume an equivalent amount of a cooked whole grain or whole wheat bread, pasta or cereal daily for three months.

The table below summarizes the changes that occurred over the three-month period in each group, and whether the improvement in the bean group was significantly greater than that in the grain group:

Grain Group

Bean Group

Greater improvement in bean group?

Fiber intake (g/1000 calories)

+1.9

+10

Yes

Glycemic load of overall diet

-5

-48

Yes

HbA1c

-0.3%

-0.5%

Yes

Body weight (lbs.)

-4.4

-5.7

Yes

Fasting blood glucose (mg/dl)

-7

-9

Yes

Triglycerides (mg/dl)

-9

-21

Yes

Total cholesterol (mg/dl)

-2

-9

Yes

Systolic blood pressure
(top number, mmHg)

No change

-4

Yes

Diastolic blood pressure
(bottom number, mmHg)

No change

-3

Yes

Heart rate (beats/min.)

-0.6

-3.4

Yes

10-year Framingham coronary heart disease risk score

-0.5

-1.1

Yes

Fiber and Glycemic load (GL)
As you can see from the table, the bean group’s fiber intake increased more and GL decreased dramatically more compared to the grain group. This highlights important nutritional differences between beans and whole grains. When it comes to fiber content, even intact whole grains don’t even come close to beans. Plus, much of the starch in beans is resistant starch and slowly digestible starch, which limits the overall glycemic effect of the carbohydrate in beans and are fermented into anti-cancer compounds in the colon. Beans are also higher in resistant starch than most grains.

Glycemic control
Hemoglobin A1c, or HbA1C is a measure of the percentage of the hemoglobin in the blood that has been glycated (has had a sugar molecule added to it); the higher your blood glucose, the more glycation occurs. The HbA1C result is an indicator of blood glucose levels over the previous three months. After three months on the bean-enriched or grain-enriched diets, this measure of long-term glycemic control was improved in both groups, but a greater improvement was seen in the bean group.

Although it may seem small, a 0.5% decrease in HbA1C is actually quite large, considering that a “healthy” (nondiabetic) A1C is below 6.0%, and a poorly controlled diabetic level is 8.0% or higher. The authors note that A1C reductions in the range of 0.5-1% translate into significant risk reductions for complications such as kidney damage.3,4 A small improvement in HbA1C (like the half-point improvement here) is very significant, as it could represent years of lifespan gained or lost. Beans as the major starch source in the diet have the potential to make a huge positive impact on the long-term health of diabetics.

These improvements in health are cumulative with other dietary changes that improve HbA1C. So there is a small improvement from more beans and squashes, a small improvement from berries and greens, a small improvement from using nuts and seeds, and a small improvement from not snacking. All these small improvements, which individually may seem like just a few tenths in HbA1C, cumulatively result in massive benefits and for most, the end of diabetes.

Blood pressure and heart disease risk
People who eat more beans tend to have lower blood pressure (not to mention greater fiber and mineral intake, lower body weight, and smaller waist circumference).5 Beans are rich in fiber (especially soluble fiber) and minerals, and low in GL — characteristics that have anti-hypertensive effects.6,7,8,1,9,10
The decrease in blood pressure in the bean group significantly improved their calculated Framingham risk score, an estimate of heart disease risk over the next ten years. This is an extremely important point, since most diabetics die of heart disease or stroke.11

Comparing two healthful food groups: grains are good, beans are better.
When diabetics switch from white flour, sugar and white rice to whole grains, they get significant health benefits. Plus, even when they switch from white potato to whole grains they get significant glycemic and other benefits, since whole grains have a comparatively lower glycemic index and more fiber than white potato.12

This study shows that when diabetics rely on beans as their primary carbohydrate source, they get even more benefits than with whole grains; more evidence of how special beans are — their nutritional superiority as a carbohydrate source.

In the End of Diabetes reversal program, when choosing carbohydrate sources I recommend:

No white flour, white rice or white potato

Small amounts of whole grains

More kiwi, berries, pomegranate, squash and beans

Of course, these carbohydrate sources should be consumed in conjunction with plenty of low-calorie vegetables — greens, eggplant, onions, mushrooms, tomatoes, etc., plus nuts and seeds daily for a phytochemical-rich, low-glycemic dietary profile with substantial anti-cancer and cardiovascular benefits.